Atrial flutter can cause false-positive ***ACUTE MI SUSPECTED*** interpretive statements

I first heard about this issue a couple of years ago in a webinar at the D2B Alliance website. Since then I have seen it several times in my own EMS system.

I also mentioned it when I commented on:

Review of Factors Associated With False-Positive Emergency Medical Services Triage for Percutaneous Coronary Intervention

According to that study the most common factors associated with false positives statements were:

  • A specific brand of one of three monitors used in the system
  • Sinus tachycardia
  • Missing lead recording on 12-lead printout
  • Atrial fibrillation
  • Female gender
  • Poor ECG baseline
  • A discussion ensues during

The authors make this important statement:

“Poor ECG baseline and failure to record all 12 leads for machine algorithm interpretation are false-positive associated variables that can be addressed by improved quality in field acquisition of 12-leads.”

It can’t be said often enough! That’s why I’m always harping on achieving excellent data quality!

The authors continue:

“Variables more difficult to address are sinus tachycardia and atrial fibrillation, which had a tendency to be wrongly interpreted by machine algorithm as acute MI.”

In response to that statement I made this comment:

“It would be interesting to know if they are including atrial flutter in with atrial fibrillation. Either way the message is clear. The specificity of the computerized interpretive algorithms is highest when a tachycardia is not present.”

The reason I questioned whether or not atrial flutter was included with atrial fibrillation is simple. Many times I have seen atrial flutter trigger a false-positive ***ACUTE MI SUSPECTED*** message on the LP12 but I can’t think of a time atrial fibrillation cause a false-positive statement (when poor data quality was not present).

Consider these cases that occurred in the past week.

Case #1

In this case the paramedic immediately realized the ***ACUTE MI SUSPECTED*** message was being caused by underlying atrial flutter. A “STEMI Alert” was not called from the field and the patient was not sent to the cath lab.

Case #2

This case was a little more difficult because 2:1 atrial flutter more difficult to recognize than 4:1 atrial flutter. It also must be said that this patient was “sicker” and presented very much like ACS. A “STEMI Alert” was called from the field and the patient ended up in the cath lab. No significant lesions were noted with angiography.

The point isn’t to blame the paramedic from the second case. A board certified emergency physician and a cardiologist both had to agree that this patient needed emergent angiography.

It’s easy to criticize individual paramedics especially when they’re from other EMS systems. What’s hard is to create quality improvement feedback mechanisms so that every call can be a learning opportunity.

There are two kinds of EMS systems in this world: those that make mistakes and those that have no idea whether or not they make mistakes (unless they receive a complaint).

Strive to be the former because anyone can be the latter.

5 Comments

  • Christopher says:

    Second ECG is tough! Rate and p-axis in II/III can lead you to 2:1 flutter. Also the T-waves are certainly strange looking. I think the only thing holding me back from a STEMI call is the rate on that one.

  • Christopher says:

    Another thing that a-fib/flutter can mess with is synchronized cardioversion. Resuscitation recently had a case where an ED used a Philips MRx set to sync through the pads and the R-wave detection kept picking up the fib/flutter waves as well, delivered a shock, caused R-on-T, v-fib…and thankfully a successful resuscitation.

    Sodeck GH, Huber J, Stöllberger C. Electrical cardioversion – misinterpretation of the R-wave. Resuscitation. 2011 Jan;82(1):135-6.

  • Mike Sherriff says:

    I too have had 2:1 A-Flutter read incorrectly as STEMI, on a Zoll.

  • speaking of a-flutter, when i review ekgs i’ve noticed the LP12s love to interpret VT as a-flutter.

  • Banery says:

    There always you want to a 740 problem during the installation.
    The MAC compatibility means that that Dub Turbo software
    can be powered by an iPad.

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EMS 12-Lead

Cardiac Rhythm Analysis, 12-Lead ECG Interpretation, Resuscitation
Comments
Justin
Rate Related VS. Primary ST-T Changes:
I'm not sold on true A-Fib, as there is a fusion beat/PAC visible in lead V1, additionally I think that the "U" waves are possibly atrial activity. This pt could be having a fib/ flutter pattern; but its hard to say without slowing down the rate and getting expert consultation from a cardiologist. I Would…
2014-09-22 23:20:29
Billy Bob
Rate Related VS. Primary ST-T Changes:
I think I will have to agree with Michael; I just don't see all that much evidence of WPW; typically with WPW & AF the complexes vary in width and morphology due to the combination of the accessory pathway and normal pathways which I just don't see here. The rate doesn't seem to match what…
2014-09-22 19:02:24
Christopher
59 year old male: chest pressure – Conclusion
I read back over the details on this case and they didn't include whether or not the patient was Left-dominant. Your hunch is probably correct!
2014-09-22 12:55:42
Jonathan
Magnesium and Cardiac Action Potential
I have a background in biochemistry, and so am able to navigate the medical science more than someone without this background. My mom has atrial fibrillation, and so I decided to do some investigation. I am AMAZED to find out how little her primary care doctor knows about Magnesium/Potassium/Calcium concentrations as they pertain to Atrial…
2014-09-22 03:46:58
Jeff
Rate Related VS. Primary ST-T Changes:
He's complaining of 10/10 chest pain that coincided with palpitations with a HR of 206 that is probably A-Fib. I am guessing that if you correct his rate you will allow his myocardium to become perfused again and his chest pain will subside. I would pre-sedate him with Midazolam 2mg and electrically cardiovert starting @…
2014-09-21 19:17:36

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